SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d9747793500b6944afc9495abc3b1815a967febf0eb1078b816af1181e491c' 
  AND token = 'rrWIgzMVYTnce+6t/HD/3nsvFXai3/8GibK2v7STyB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}