SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a19bf9b94fa6d94455498cd43fd50d4cb1e6db2255bf68f4836773c0c2c6d67c' 
  AND token = 'hrk/PLwyCu3rTFqax8OBKWOrvNLBFAAVgppM15mzMzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00070

JSON explain

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