SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c9e2da8d82855f1523a98675954fb36c17256b9d58f3bc667f3dd0389a9d78b' 
  AND token = 'T/3s6FCeHrSzqq3OIcOMWJxu96SYYUUkNdICEqwOXkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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