SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8f0edd3aafce798a6304ee8fff56df572af843917751c98b295da3d8439e56ca' 
  AND token = '0iVppWqfcWDSmPwrBuzwdn3A6PK9SU1YrrTzAqrVQHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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