SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5369ab6c529026f1ea8b5f3342216cc563ea1547993c6012c2397604b4a39da2' 
  AND token = 'nKU+1FhelrapoSKjZOMHJOHxX9LW1nuOlF/d3Oev+jU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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