SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4351ece02c84efb86bce8f8101808cc02c5295a395af44926f7da03fcf58751' 
  AND token = 'srycK02lGG3VEzCDMMJE/7a/4GEKPx2MofzOxx2xH/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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