SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e4275c61496817e2679f6ec5fb14ca47e2ab84d636742b87b4b5b13922cebae' 
  AND token = 'hRFHKOUlCs0zM+RUTN7ZDafGlWhBlvB7oTt+BGssAzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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