SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5a71edbf486e7ada7669ac46e19620b16d562c7835b30ac46470d5733f026f6' 
  AND token = 'GPXsmboEGa/Nkhp9rI0kXRYeRhfQ6FdXxAogcAqHe3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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