SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46fc130a338d7ab50160064197dbf701a52bff1484266deed43ae2d6417b0a83' 
  AND token = 'DBc7YqAUtTqsXAeo+GrOXblNb0BbICn0fTTL7OCdzEc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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