SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55e63718914af8b63bccaaafd6505c413105865cb6568355c705ea16e5716f22' 
  AND token = 'gLZS+3I1CIAhttUZmW/SHAHt6Q20lKfuQeabSSV8Mpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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