SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd15b2af40b2dd0a6713bef2db576aad53f683923f33c24b3a41884123355e0d' 
  AND token = 'XxiLovBDABHnNA+e0yAcZmLnxbpAAGVNNskxJ7gYQX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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