SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43639f67ff46be309ec15386a09bd5bd5960b5ea527438a35e90bbbfec4943ca' 
  AND token = 'NC5/jpVsNZSUZ17R7lzzGLEKVWqTHYNguDO6cMrTiQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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