SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50e2f006258f453d4318886783e47ec53d80d66f38a6dc58a957d94a5fccdb2f' 
  AND token = 'NXRls0r2+/3XCEidUF/3fJhH0a8IwXLT4QLcBm58EEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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