SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a4aa3c51c9e5ed4bba19325463f4666f3903de89ace93964a60fba16969654b' 
  AND token = 'UhJ+B5NKLkSWSjMmCnZLDqCXIzd9aZfYPTGsD7RvBN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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