SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df68aabf6f671959fe68396c289df29454130ca82de24e9f0126e5379e73fbe5' 
  AND token = '5UpQyu7n40Q74qAl34toVJxnTl7rVcvSJgxL6ZWfFKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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