SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3386edd6a9870b1b5cf01a2ab95560e986c4a4c2875d513f9903a6d32832ce44' 
  AND token = 'KYGuHD6jcmQHOGSvyOvvaBUPL1T1gy1xunAhEB9wCVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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