SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '318f65312059c9c79f79c1df42667bd52c4d05537de0dd0a5ab308cb7f87f273' 
  AND token = '1OGVh1ZqMbJ7CZrZ2cSYZHPZzqrXOCkm+s+2QrP9/rw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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