SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2d5d69f8c914239a506621423bdf2638baf3171141461dede0a02464de1cc46' 
  AND token = 'bgs548IPAcvEfWuweEsQbGgabJK/3+7P10VWvViwoZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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