SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd31df878553db4598dcadd988e4751f5473b6922f15502d1c59a63e333827d15' 
  AND token = 'GP8D6/b4sAky4+Q9VIDu95rqw7lOjCp7oxFJMtkhztY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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