SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d8f0533050f95cb516dc54c0c8e37c9b63397f2bd0bc66718df954fbef0a841' 
  AND token = 'oSdLjtoajey7EJjr/bejxVFsMo6m4OTBndAonIB+iAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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