SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5473ca0424ac9a85ed05fca4d5cda50d8a72c2a73dd98f5bf19230aa895bb947' 
  AND token = 'sHbWsMiyzNX/ss6gFQa3NrU97v55xfY+XjbKqPZchzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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