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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1ce1cfc0a7f3983d68a9ee4d79dd11bc39fae3c8aa30e64bbe29b3c399b7791' 
  AND token = 'PKiqkMpvhkLoHs25U5atnTermrf4H/no4sWKctc71U8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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