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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3cff688efbe8abe4091bd1d81aa6ca3aaf7d42659f191a95b32f8b9766ecc9a' 
  AND token = 'lVvAkgQ59BqjPF5NfF3FEqM6B8UFuP5DZrF1tWXdhrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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