SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21c104688932076a3de0ae9caabf4845ebdfab416a22211acacefa23c1b39cb5' 
  AND token = '+6hxPZi3j8iNKUaVNVceM0S7BMnC+1FSCeb2vXdF8SA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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