SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45546b350ff36a9185da9d76849d8434044aabe874fa3281f561d177173c8cbf' 
  AND token = 'jQWIKnCrv5PfBkHexRVOKfLM/jQkJvkIzkdOFA4drSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00093

JSON explain

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