SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '740358405e9878f93b8a9a0a4b9d6caa11803fdbbff8c54e6567c97ddf433a20' 
  AND token = 'eI5cC/5XRZw3bBOoXPCmxQ0Utyj0oamoBDTKl+a7AGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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