SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a536c41f686978be7b40c315ada569ea8f760d0b4412a3991c528f9b33396c6e' 
  AND token = 'xShIbyFWJmsVICpJILkbYuUqpF8eZTZkidcMppe2HQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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