SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6dd345edd4bfe59cf2c4ad03119d4ed8606b6d9fee2c7425ecc36ddea109b75' 
  AND token = 'QjflTer851S8eulZq0bAtqWOjtcIydvRkipw62Dgp08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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