SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87569215471b1923351f955c815d10d942363097755f317caa21da616c2f3f41' 
  AND token = '+SJa5btoQYt8HEC7wWF8qdX97lgYFwY6OJrLRiEdKsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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