SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c23bd36e9ec2594502b76789802951c6e5b46fdb7411319ac028cccf571c5249' 
  AND token = '34x168o+soNUJ/AYESgi9ulXg/H7AJkx3GNhr6w9vjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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