SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b54553bb09c198e983230ea99148556849538433dde1178706317fb93ca7ff4' 
  AND token = '2868dv+A3gElCdcBHwoVcR7OpYtlTN7kc7H4yNVLzug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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