SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39a13badcf300dbd207dec5aeae9a2598ea6dfba362cadebd55fcf0fe5047739' 
  AND token = 'Z9i/tUSKNIq+sHFyMLQfcH9zkv81qMyfi07MaDWaw2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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