SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6e076752b593de33ae6c9fd973be6e748688cb1be8b34c1c3cfebb81ee0b3ec' 
  AND token = 'um9OCFwqWvPA+szRrmwjIBwY+L826ejxY0GAuYrU0ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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