SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e90674b392c66843054025e526c29e559a5afca7c59d32aeea5e469827d376c0' 
  AND token = 'TnxVFfCUuWOkxmBfJ18r8UHKzvDK2h4zNb6PNqO3RQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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