SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '238dddf19dce3048befb11d3968470660bd05578ae13398661461584e5dd6433' 
  AND token = 'WpLKshJW9smydGFSNjHeERSYa43weMMHg9REtkOzO2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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