SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bc3a8b2db234e2aea44b758f88fa09ed99b7511f807fcef4f191eb909249638' 
  AND token = 'N/+sYrz5XIhec2y5LmshTpJVRaETvt+CowKiSliQLms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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