SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35814fa0013020dcbc71ddd754789e684dfe5b359950f26a94466364ce2692c8' 
  AND token = 'MTkGvFExJ3sM2xGbRAEsoYfw4F4qA/qWREkj/MeWra4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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