SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a021fed34678410f48fc675edb2fa61df131a4066d7265dfcd119a00e05aa2f5' 
  AND token = 'jq1ztu+mHJkTQyduOaYcyvDhW9jllK6jW7v5re8lAvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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