SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ef949518cbd69dbfd12888b3ca4d54667c1d6025eee2083c5e3fc6652020687' 
  AND token = '3wZAn4HJKi64eqFXXz4EJk1NZMqMjw5zht0e+rCKlQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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