SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c81bc1e4ae76e731ea4362d446c46abcc9ea3c9e9df226ab1434352eba858e1e' 
  AND token = 'j0asqPHllnMw3cVrZqC2jKi+UVVKvSEHuHEeFPAgNUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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