SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f8a099b3f15b51acc384b7135dce251fc60ae2d5795996e58288b95b943f875' 
  AND token = 'xC0QGOscYd95Rd1C+7tBctvwA3++mzo+fbiiEnzFuws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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