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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85ab8457f7cde0dd467fbb0c2a1571227085a8bd35b380e5c8d3ac8a45dbb3dd' 
  AND token = 'F74h2jUJMXtsU0BlSE1MxlrbcT9gqvlE+AO4y3K+5rI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}