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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6603eac4e94750f4e0c8c29f44e5d8786e2fbb791ef4fc90add21790d7b2d67' 
  AND token = 'gdRRdjyGW6T3LtHlvMOlcDZ5rmqBeyJejnE/Z7hMLos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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