SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5068402ec8bcf793d1132a62f71f2dbec911e5eef53ac474abb0c1c7e2863d19' 
  AND token = 'A2cOtQbzor8dcDCFwS/uUGHgvvE1mlloBcmxxqggKnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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