SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c18e1eb8480547b5c839d51643ea01614288768f70b1789a27650295877e69f0' 
  AND token = 'iBKkYa+iKdly+zeEymZV3YnjJExdME72htf0DwyB5IE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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