SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '373f77d2d1e3056bb4a6f739eafe86394c35217929977b37c2c49351d092b914' 
  AND token = 'bwXlaCmVBOGC8NHMZZ3csDKvWibO9lW+mFSYvSV7c8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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