SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a43c97f7a339c04ff23cb9d85afebd08715064571b4c1ee5541347b3b978fdf' 
  AND token = 'ZWVBCsDJZgyZ7p97mHCJxryVAzxv33jzkb6aRtHwBhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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