SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35b517e90c8236860f1036150b896f3916805b3b7f9cd85db268961d379433c8' 
  AND token = '7GElBb+HPpN3vWXMndmoPYCEEWrS0wyAActqPElokUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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