SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21ba3626965279fabd9dc9a2f8320fb7315444578bb844f71a83dc4f08f22772' 
  AND token = 'tgPWyx8Ogq6N4v7unnvJu8ijFoDSEkZ1IDjxHKG4EDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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