SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8252f581fd62bd2741a4eb6bc22ec2799bacb43279f53894f54a5a44335b713' 
  AND token = '7IKOsiYHuWVr0Do+9gZjtPyzCuJXF+WeIhI3TkZEDQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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