SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f3b2a7b0269c92c8bf2dfd2cdc27ca81f38137578c6913a8958df1f6b7cc75' 
  AND token = 'nYdTwI5IIU9aaFOkzK+2akUAScIkJqquvt/HsOhHOxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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