SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '762d34b46d0792cefba518ece1fd45490c7fd19b3eca320442085b098d4f1659' 
  AND token = 'ZfM6yP/+3MWxVlyAdicXW5YpiKw7jgEDVhXHT7stlhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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