SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '215b348f7f1c6b252388722c255ca5f58916b4489094bbf090754e676daf9bda' 
  AND token = 'U/JqxlG8DMGhAkWO6ZFZsWxRSTBMsI8oMOPRaq9Avec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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