SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c389e05db9bc7259e17853e421f4a5eae9c23d47f66880a786b607d1551e54c' 
  AND token = 'DEZyUeXFZRdYRbKCSvSmnoEUJkUBo1JyNbhfmEPfN0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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