SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a2622a528f2a2869bbb883593f3ab8a4136fdab5204c43349cd25349c986429' 
  AND token = 'xsgjDRFmeqZxSDuiGUWMK3o+fp1jxFfH56iyzcIwraM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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