SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dbe35ad18fad17effcadbd4b83a15c58456d32e755a4dc9ed1f67c8f1b367a3' 
  AND token = 'c+IgHpt6x+RgFLSqw2/mVBfP5ChjCEwk4vY6bj9StBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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