SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fffd6655265cab2d436520e1dbbfa8016d3ab06845998687929fde85d900583' 
  AND token = 'gPgvP4wrhiNOIN+aFViAQAvLKBsv7GPowla7wCSV0a0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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