SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5913d11eaec90a3ba1dcd27924e30d7cb3953f2e49870aee6ff4fcaf3b7585ea' 
  AND token = 'UBEfo8OFJNdKj1ur4OVNmNPEArZTw/epqwoRd+yjKUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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