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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '576b8c98054e1d1c7912d0b1b0afb09e55c88c427dec62d5eaf79d021919318b' 
  AND token = '1gUjsLrgx4CqHykPPFWoztQJ0Ih72c+rD6p77YKKpLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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