SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '345affac1151411abaa35ae5a5e0b8d759720ff3218c6d0897f734d120c0f519' 
  AND token = 'L5CSKFXFyRrqOvvCdma3yUn9Q8BkR3RxKDOCngmGDCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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