SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fba4bf1fc3f234b3e7775ee1b2cb0ba868fb4c1e68bf3108fdca08b83273ef9' 
  AND token = 'L5T51CjlfWzqqtcFTYpWQn9zcPOfZT4bz+LT5jTXPDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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