SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afc249175929edee6536d0b486e4679080b15a22092bea05e6079dcd4dd4cf93' 
  AND token = '6EGCJCSmmBSZ/ZS1pgLrWjroLcPMULYRNz0HauiBLIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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