SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ae2d7fd05efb5ddebecea63347e6012afb98ee58e72a85938b73140cc6333f3' 
  AND token = 'Kk3TFBKjtSy8u402XscKeoYPq2hur9eLlhL2muWnKlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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