SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8903749920a232509801f740b1cb2944ab0e35540cf60013056e3976a6329b7d' 
  AND token = 'sasAGWXpyUR6DBk8MHRv6ay9khvm0QezGhmYFDXQPwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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