SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d1fa78674902e971d372eaff34438f771d54d62631c37b83f22d6140485aafd' 
  AND token = '+5YQ8cOBWOYHHt1Pfsrv+h0nAUPkWJgK9kdLX+iOjgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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