SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56f8d551d8804158fcf94e5335d07fd38c91b98b1bc4d7cc5add722bec87ea6f' 
  AND token = 'vrQ1Lwl+dueXckx6tTzqH61kCQ85VBLzgxEXQ5nd8mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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